21155201121 has 16 divisors (see below), whose sum is σ = 28566492480. Its totient is φ = 13924162560.

The previous prime is 21155201107. The next prime is 21155201131. The reversal of 21155201121 is 12110255112.

It is not a de Polignac number, because 21155201121 - 2¹¹ = 21155199073 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21155201131) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 120826 + ... + 238556.

It is an arithmetic number, because the mean of its divisors is an integer number (1785405780).

Almost surely, 2^21155201121 is an apocalyptic number.

It is an amenable number.

21155201121 is a deficient number, since it is larger than the sum of its proper divisors (7411291359).

21155201121 is a wasteful number, since it uses less digits than its factorization.

21155201121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 118496.

The product of its (nonzero) digits is 200, while the sum is 21.

Adding to 21155201121 its reverse (12110255112), we get a palindrome (33265456233).

The spelling of 21155201121 in words is "twenty-one billion, one hundred fifty-five million, two hundred one thousand, one hundred twenty-one".